A chipper disc and knife assembly utilizing double-edged reversible and disposable chipper knives is disclosed in Carpenter et al. U.S. Pat. No. 4,771,718. The knife featured in the Carpenter et al. assembly includes an elongated key-receiving channel on one of its sides which is relied upon to position the knife in place with respect to the chipper disc. While the assembly provides a double-edged chipper knife which can be securely mounted in a chipper disc, the knife itself cannot be reground and sharpened on the primary bevel while maintaining its cutting edge in the same relative position with respect to the surface of the chipper disc and anvil. This is because the counterknife in the Carpenter et al. assembly includes a key which, by its very nature, precludes relative motion radially between the knife and the mounting.
Knife and disc assemblies are known which utilize a knife having position adjusting serrations such that the knife can be adjustably positionable relative to a knife holding means. One such assembly is disclosed in Haller et al. U.S. Pat. No. 4,423,758. In the Haller et al. assembly, a reversible knife is mounted between a counterknife and a knife clamp. The knife has a flat surface which bears against a flat surface on the clamp. The opposite surface of the knife includes indented serrations which engage protruding serrations on the counterknife. Protruding serrations on a counterknife, however, tend to interfere with the cutting operation. They also tend to produce erratic chip sizes and generally interfere with the efficient operation of the assembly.
Serrations on the front side of a knife will also prevent it from being reground and sharpened, as the serrations would interfere with the grinding of the necessary edge reliefs as the body of the knife is reduced in size.
It is thus a principal object of the present invention to provide chipper apparatus of the type described with a reversible and sharpenable chipper knife and a mounting therefor, wherein the knife itself is adjustably positionable relative to the mounting such that the knife can be reground while maintaining its edge at the correct position relative to the surface of the chipper and the associated anvil.
It is a further object of the present invention to provide chipper apparatus of the type described wherein an adjustably positionable knife includes a bearing surface on its back side having indented serrations adapted cooperatively to engage protruding serrations on a clamping surface of a knife clamp.
A still further object of the present invention is to provide chipper apparatus of the type described having an adjustably positionable knife, with an absence of serrations on its front face, the apparatus thus being suitable for use with a counterknife without serrations, such that the assembly will not interfere in any way with the production of desirably sized wood chips.